Electrochemical cells, such as fuel cells, include pathways for the transport of charged species. Ions from electrochemical reactions are transported through an ion-exchange membrane of a fuel cell, such as a proton exchange membrane, and electrons are transferred between adjacent fuel cells. Specifically, a path for proton conductivity can be integrated within the fuel cell while a path for electron conductivity is created between adjacent fuel cells to provide an electrical circuit from the overall positive and negative electrical connections of the fuel cell device. Bipolar fuel cells are arranged to provide an electrical current flow in a direction opposite to an ion flow through the membrane. Alternately, edge-collected fuel cells provide electrical current flow parallel to the membrane while ion flow occurs through the membrane.
In either case, edge collected or bipolar, the electrolyte serves as both a proton conductor and an electrical insulator, i.e. the electrolyte separates the two reaction electrodes and prevents the short circuit of electrical current between the two. However, one function of the electrical insulation is to prevent the electrical short circuit of the two electrodes of a unit fuel cell with each other.
An alternative class of fuel cell architecture is emerging for use in micro fuel cell applications that results in a thin layered fuel cell structure with neighboring fuel cells arranged adjacent each other, such as in an array. When a fuel cell layer of this variety incorporates more than one fuel cell, some form of electrically insulating material must exist in the same plane as the electrodes to prevent electrical short circuiting between neighboring cells. The planar fuel cell array includes multiple fuel cells which have like electrodes arranged next to each other on the same face of the fuel cell layer. A requirement is to prevent the electrical short circuit of adjacent like electrodes, such as by adding insulating materials that detract from the overall active area of the array. Current designs allocate significant portions of space to insulating materials that do not contribute to energy conversion. Further, the addition of an explicit insulating material adds both cost and complexity to the fuel cell design.